Preparation of dimeric model compounds of lignin

1996 ◽  
Vol 32 (1) ◽  
pp. 98-99
Author(s):  
L. S. Smirnova ◽  
Kh. A. Abduazimov
Keyword(s):  
Model Compounds ◽  
Dimeric Model

Lignin-degrading enzymes

1987 ◽  
Vol 321 (1561) ◽  
pp. 461-474 ◽  
Keyword(s):  
Lignin Biodegradation ◽  
Major Research ◽  
Model Compounds ◽  
Peroxidase Isoenzymes ◽  
Cation Radicals ◽  
Radical Intermediates ◽  
Degrading Enzymes ◽  
Potential Applications ◽  
Full Complement ◽  
Dimeric Model

The substantial potential applications of lignin-degrading microbes and enzymes have spurred research on lignin biodegradation in recent years. As described here, that research has led to the discovery in the basidiomycete Phanerochaete chrysosporium of the first lignin-degrading enzymes and elucidation of their mode of action. A family of powerful extracellular peroxidase isoenzymes has been the focus of most investigations. The key catalytic reaction of these glycoproteins, in the presence of hydrogen peroxide, is one-electron oxidation of aromatic nuclei, generating unstable aryl cation radicals. These decompose via a number of reactions, which have been elucidated with dimeric model compounds for lignin. The involvement of carboncentred and peroxyl free-radical intermediates has been established. The peroxyl intermediates result from the addition of molecular oxygen to the C-centred radicals. Strong evidence for a classical peroxidase-type catalytic cycle of the ligninases has been obtained. The major research need is to identify the full complement of enzymes needed to degrade lignin to small fragments; this degradation is not accomplished by the isolated ligninases or by the crude extracellular mixture of enzymes secreted by cultures as they degrade lignin.

Carbon-13 NMR Chemical Shifts of Dimeric Model Compounds of Poly(propylene Oxide):  A Proof of Existence of the (C−H)···O Attraction

2001 ◽  
Vol 105 (13) ◽  
pp. 3277-3283 ◽  
Author(s):  
Yuji Sasanuma ◽  
Taisuke Iwata ◽  
Yasukazu Kato ◽  
Haruhisa Kato ◽  
Takashi Yarita ◽  
...  
Keyword(s):  
Propylene Oxide ◽  
Chemical Shifts ◽  
Model Compounds ◽  
Nmr Chemical Shifts ◽  
Poly Propylene ◽  
Dimeric Model

Polarographically Active Structural Fragments of Lignin. II. Dimeric Model Compounds and Lignins

2005 ◽  
Vol 24 (3) ◽  
pp. 263-278 ◽  
Author(s):  
Edward Evstigneyev ◽  
Sergey Shevchenko ◽  
Helene Mayorova ◽  
Andrew Platonov
Keyword(s):  
Model Compounds ◽  
Dimeric Model

Exterplex formation of poly(3,6-di-tert-butyl-9-vinylcarbazole) and its dimeric model compounds with dimethyl terephthalate studied by fluorescence spectroscopy

1993 ◽  
Vol 26 (6) ◽  
pp. 1411-1416 ◽  
Author(s):  
Yoshinobu Tsujii ◽  
Kazukiyo Takami ◽  
Akira Tsuchida ◽  
Shinzaburo Ito ◽  
Masahide Yamamoto
Keyword(s):  
Fluorescence Spectroscopy ◽  
Model Compounds ◽  
Tert Butyl ◽  
Dimethyl Terephthalate ◽  
Dimeric Model

scholarly journals Ligninase of Phanerochaete chrysosporium. Mechanism of its degradation of the non-phenolic arylglycerol β-aryl ether substructure of lignin

1986 ◽  
Vol 236 (1) ◽  
pp. 279-287 ◽  
Author(s):  
T K Kirk ◽  
M Tien ◽  
P J Kersten ◽  
M D Mozuch ◽  
B Kalyanaraman
Keyword(s):  
Aromatic Ring ◽  
Cation Radical ◽  
Aryl Ether ◽  
Model Compounds ◽  
Radical Intermediate ◽  
Cation Radicals ◽  
Basic Model ◽  
Lignin Model ◽  
Time Courses ◽  
Dimeric Model

This study examined the ligninase-catalysed degradation of lignin model compounds representing the arylglycerol beta-aryl ether substructure, which is the dominant one in the lignin polymer. Three dimeric model compounds were used, all methoxylated in the 3- and 4-positions of the arylglycerol ring (ring A) and having various substituents in the beta-ether-linked aromatic ring (ring B), so that competing reactions involving both rings could be compared. Studies of the products formed and the time courses of their formation showed that these model compounds are oxidized by ligninase (+ H2O2 + O2) in both ring A and ring B. The major consequence with all three model compounds is oxidation of ring A, leading primarily to cleavage between C(alpha) and C(beta) (C(alpha) being proximal to ring A), and to a lesser extent to the oxidation of the C(alpha)-hydroxy group to a carbonyl group. Such C(alpha)-oxidation deactivates ring A, leaving only ring B for attack. Studies with C(alpha)-carbonyl model compounds corresponding to the three basic model compounds revealed that oxidation of ring B leads in part to dealkoxylations (i.e. to cleavage of the glycerol beta-aryl ether bond and to demethoxylations), but that these are minor reactions in the model compounds most closely related to lignin. Evidence is also given that another consequence of oxidation of ring B in the C(alpha)-carbonyl model compounds is formation of unstable cyclohexadienone ketals, which can decompose with elimination of the beta-ether-linked aromatic ring. The mechanisms proposed for the observed reactions involve initial formation of aryl cation radicals in either ring A or ring B. The cation radical intermediate from one of the C(alpha)-carbonyl model compounds was identified by e.s.r. spectroscopy. The mechanisms are based on earlier studies showing that ligninase acts by oxidizing appropriately substituted aromatic nuclei to aryl cation radicals [Kersten, Tien, Kalyanaraman & Kirk (1985) J. Biol. Chem. 260, 2609-2612; Hammel, Tien, Kalyanaraman & Kirk (1985) J. Biol. Chem. 260, 8348-8353].

scholarly journals Studies on the Enzymatic Degradation of Lignin. The Action of Peroxidase and Laccase on Monomeric and Dimeric Model Compounds.

1973 ◽  
Vol 27 ◽  
pp. 2909-2922 ◽  
Author(s):  
Josef Gierer ◽  
Augustine E. Opara ◽  
Johan Mjöberg ◽  
Salo Gronowitz ◽  
Jouko Koskikallio ◽  
...  
Keyword(s):  
Enzymatic Degradation ◽  
Model Compounds ◽  
Dimeric Model

Secondary pyrolysis pathway of monomeric aromatics resulting from oxidized β-O-4 lignin dimeric model compounds

2017 ◽  
Vol 168 ◽  
pp. 11-19 ◽  
Author(s):  
Weikun Jiang ◽  
Jiangyong Chu ◽  
Shubin Wu ◽  
Lucian A. Lucia
Keyword(s):  
Model Compounds ◽  
Dimeric Model
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